Kawashima Shopping Arcade (川島商店街) — Nakano 川島商店街
In the drama it appears in episodes 3 and 4: the Yamagataya grocer's and the small Cosmo-kun municipal square, where the neighbourhood festival is held, are along this same street.
An old shopping street in Yayoichō, at the southern end of Nakano, ten minutes on foot from Nakano-shimbashi Station; it keeps the atmosphere of the Sixties and is also known as ‘Cosmo Station Kawashima’. The coordinates mark the entrance to the arcade.
Tokyo
Nakano-sakaue, Nakano-shimbashi
Kotaro Lives Alone
In the drama it appears in episodes 3 and 4: the Yamagataya grocer's and the small Cosmo-kun municipal square, where the neighbourhood festival is held, are along this same street.
All the places from Kotaro Lives Alone
https://theanimetrip.com/luoghi/galleria-commerciale-kawashima-nakano